1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2005,2006,2007,2008 IBM Corporation 4 * 5 * Authors: 6 * Mimi Zohar <zohar@us.ibm.com> 7 * Kylene Hall <kjhall@us.ibm.com> 8 * 9 * File: ima_crypto.c 10 * Calculates md5/sha1 file hash, template hash, boot-aggreate hash 11 */ 12 13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 14 15 #include <linux/kernel.h> 16 #include <linux/moduleparam.h> 17 #include <linux/ratelimit.h> 18 #include <linux/file.h> 19 #include <linux/crypto.h> 20 #include <linux/scatterlist.h> 21 #include <linux/err.h> 22 #include <linux/slab.h> 23 #include <crypto/hash.h> 24 25 #include "ima.h" 26 27 /* minimum file size for ahash use */ 28 static unsigned long ima_ahash_minsize; 29 module_param_named(ahash_minsize, ima_ahash_minsize, ulong, 0644); 30 MODULE_PARM_DESC(ahash_minsize, "Minimum file size for ahash use"); 31 32 /* default is 0 - 1 page. */ 33 static int ima_maxorder; 34 static unsigned int ima_bufsize = PAGE_SIZE; 35 36 static int param_set_bufsize(const char *val, const struct kernel_param *kp) 37 { 38 unsigned long long size; 39 int order; 40 41 size = memparse(val, NULL); 42 order = get_order(size); 43 if (order >= MAX_ORDER) 44 return -EINVAL; 45 ima_maxorder = order; 46 ima_bufsize = PAGE_SIZE << order; 47 return 0; 48 } 49 50 static const struct kernel_param_ops param_ops_bufsize = { 51 .set = param_set_bufsize, 52 .get = param_get_uint, 53 }; 54 #define param_check_bufsize(name, p) __param_check(name, p, unsigned int) 55 56 module_param_named(ahash_bufsize, ima_bufsize, bufsize, 0644); 57 MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size"); 58 59 static struct crypto_shash *ima_shash_tfm; 60 static struct crypto_ahash *ima_ahash_tfm; 61 62 int __init ima_init_crypto(void) 63 { 64 long rc; 65 66 ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0); 67 if (IS_ERR(ima_shash_tfm)) { 68 rc = PTR_ERR(ima_shash_tfm); 69 pr_err("Can not allocate %s (reason: %ld)\n", 70 hash_algo_name[ima_hash_algo], rc); 71 return rc; 72 } 73 pr_info("Allocated hash algorithm: %s\n", 74 hash_algo_name[ima_hash_algo]); 75 return 0; 76 } 77 78 static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo) 79 { 80 struct crypto_shash *tfm = ima_shash_tfm; 81 int rc; 82 83 if (algo < 0 || algo >= HASH_ALGO__LAST) 84 algo = ima_hash_algo; 85 86 if (algo != ima_hash_algo) { 87 tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0); 88 if (IS_ERR(tfm)) { 89 rc = PTR_ERR(tfm); 90 pr_err("Can not allocate %s (reason: %d)\n", 91 hash_algo_name[algo], rc); 92 } 93 } 94 return tfm; 95 } 96 97 static void ima_free_tfm(struct crypto_shash *tfm) 98 { 99 if (tfm != ima_shash_tfm) 100 crypto_free_shash(tfm); 101 } 102 103 /** 104 * ima_alloc_pages() - Allocate contiguous pages. 105 * @max_size: Maximum amount of memory to allocate. 106 * @allocated_size: Returned size of actual allocation. 107 * @last_warn: Should the min_size allocation warn or not. 108 * 109 * Tries to do opportunistic allocation for memory first trying to allocate 110 * max_size amount of memory and then splitting that until zero order is 111 * reached. Allocation is tried without generating allocation warnings unless 112 * last_warn is set. Last_warn set affects only last allocation of zero order. 113 * 114 * By default, ima_maxorder is 0 and it is equivalent to kmalloc(GFP_KERNEL) 115 * 116 * Return pointer to allocated memory, or NULL on failure. 117 */ 118 static void *ima_alloc_pages(loff_t max_size, size_t *allocated_size, 119 int last_warn) 120 { 121 void *ptr; 122 int order = ima_maxorder; 123 gfp_t gfp_mask = __GFP_RECLAIM | __GFP_NOWARN | __GFP_NORETRY; 124 125 if (order) 126 order = min(get_order(max_size), order); 127 128 for (; order; order--) { 129 ptr = (void *)__get_free_pages(gfp_mask, order); 130 if (ptr) { 131 *allocated_size = PAGE_SIZE << order; 132 return ptr; 133 } 134 } 135 136 /* order is zero - one page */ 137 138 gfp_mask = GFP_KERNEL; 139 140 if (!last_warn) 141 gfp_mask |= __GFP_NOWARN; 142 143 ptr = (void *)__get_free_pages(gfp_mask, 0); 144 if (ptr) { 145 *allocated_size = PAGE_SIZE; 146 return ptr; 147 } 148 149 *allocated_size = 0; 150 return NULL; 151 } 152 153 /** 154 * ima_free_pages() - Free pages allocated by ima_alloc_pages(). 155 * @ptr: Pointer to allocated pages. 156 * @size: Size of allocated buffer. 157 */ 158 static void ima_free_pages(void *ptr, size_t size) 159 { 160 if (!ptr) 161 return; 162 free_pages((unsigned long)ptr, get_order(size)); 163 } 164 165 static struct crypto_ahash *ima_alloc_atfm(enum hash_algo algo) 166 { 167 struct crypto_ahash *tfm = ima_ahash_tfm; 168 int rc; 169 170 if (algo < 0 || algo >= HASH_ALGO__LAST) 171 algo = ima_hash_algo; 172 173 if (algo != ima_hash_algo || !tfm) { 174 tfm = crypto_alloc_ahash(hash_algo_name[algo], 0, 0); 175 if (!IS_ERR(tfm)) { 176 if (algo == ima_hash_algo) 177 ima_ahash_tfm = tfm; 178 } else { 179 rc = PTR_ERR(tfm); 180 pr_err("Can not allocate %s (reason: %d)\n", 181 hash_algo_name[algo], rc); 182 } 183 } 184 return tfm; 185 } 186 187 static void ima_free_atfm(struct crypto_ahash *tfm) 188 { 189 if (tfm != ima_ahash_tfm) 190 crypto_free_ahash(tfm); 191 } 192 193 static inline int ahash_wait(int err, struct crypto_wait *wait) 194 { 195 196 err = crypto_wait_req(err, wait); 197 198 if (err) 199 pr_crit_ratelimited("ahash calculation failed: err: %d\n", err); 200 201 return err; 202 } 203 204 static int ima_calc_file_hash_atfm(struct file *file, 205 struct ima_digest_data *hash, 206 struct crypto_ahash *tfm) 207 { 208 loff_t i_size, offset; 209 char *rbuf[2] = { NULL, }; 210 int rc, rbuf_len, active = 0, ahash_rc = 0; 211 struct ahash_request *req; 212 struct scatterlist sg[1]; 213 struct crypto_wait wait; 214 size_t rbuf_size[2]; 215 216 hash->length = crypto_ahash_digestsize(tfm); 217 218 req = ahash_request_alloc(tfm, GFP_KERNEL); 219 if (!req) 220 return -ENOMEM; 221 222 crypto_init_wait(&wait); 223 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | 224 CRYPTO_TFM_REQ_MAY_SLEEP, 225 crypto_req_done, &wait); 226 227 rc = ahash_wait(crypto_ahash_init(req), &wait); 228 if (rc) 229 goto out1; 230 231 i_size = i_size_read(file_inode(file)); 232 233 if (i_size == 0) 234 goto out2; 235 236 /* 237 * Try to allocate maximum size of memory. 238 * Fail if even a single page cannot be allocated. 239 */ 240 rbuf[0] = ima_alloc_pages(i_size, &rbuf_size[0], 1); 241 if (!rbuf[0]) { 242 rc = -ENOMEM; 243 goto out1; 244 } 245 246 /* Only allocate one buffer if that is enough. */ 247 if (i_size > rbuf_size[0]) { 248 /* 249 * Try to allocate secondary buffer. If that fails fallback to 250 * using single buffering. Use previous memory allocation size 251 * as baseline for possible allocation size. 252 */ 253 rbuf[1] = ima_alloc_pages(i_size - rbuf_size[0], 254 &rbuf_size[1], 0); 255 } 256 257 for (offset = 0; offset < i_size; offset += rbuf_len) { 258 if (!rbuf[1] && offset) { 259 /* Not using two buffers, and it is not the first 260 * read/request, wait for the completion of the 261 * previous ahash_update() request. 262 */ 263 rc = ahash_wait(ahash_rc, &wait); 264 if (rc) 265 goto out3; 266 } 267 /* read buffer */ 268 rbuf_len = min_t(loff_t, i_size - offset, rbuf_size[active]); 269 rc = integrity_kernel_read(file, offset, rbuf[active], 270 rbuf_len); 271 if (rc != rbuf_len) { 272 if (rc >= 0) 273 rc = -EINVAL; 274 /* 275 * Forward current rc, do not overwrite with return value 276 * from ahash_wait() 277 */ 278 ahash_wait(ahash_rc, &wait); 279 goto out3; 280 } 281 282 if (rbuf[1] && offset) { 283 /* Using two buffers, and it is not the first 284 * read/request, wait for the completion of the 285 * previous ahash_update() request. 286 */ 287 rc = ahash_wait(ahash_rc, &wait); 288 if (rc) 289 goto out3; 290 } 291 292 sg_init_one(&sg[0], rbuf[active], rbuf_len); 293 ahash_request_set_crypt(req, sg, NULL, rbuf_len); 294 295 ahash_rc = crypto_ahash_update(req); 296 297 if (rbuf[1]) 298 active = !active; /* swap buffers, if we use two */ 299 } 300 /* wait for the last update request to complete */ 301 rc = ahash_wait(ahash_rc, &wait); 302 out3: 303 ima_free_pages(rbuf[0], rbuf_size[0]); 304 ima_free_pages(rbuf[1], rbuf_size[1]); 305 out2: 306 if (!rc) { 307 ahash_request_set_crypt(req, NULL, hash->digest, 0); 308 rc = ahash_wait(crypto_ahash_final(req), &wait); 309 } 310 out1: 311 ahash_request_free(req); 312 return rc; 313 } 314 315 static int ima_calc_file_ahash(struct file *file, struct ima_digest_data *hash) 316 { 317 struct crypto_ahash *tfm; 318 int rc; 319 320 tfm = ima_alloc_atfm(hash->algo); 321 if (IS_ERR(tfm)) 322 return PTR_ERR(tfm); 323 324 rc = ima_calc_file_hash_atfm(file, hash, tfm); 325 326 ima_free_atfm(tfm); 327 328 return rc; 329 } 330 331 static int ima_calc_file_hash_tfm(struct file *file, 332 struct ima_digest_data *hash, 333 struct crypto_shash *tfm) 334 { 335 loff_t i_size, offset = 0; 336 char *rbuf; 337 int rc; 338 SHASH_DESC_ON_STACK(shash, tfm); 339 340 shash->tfm = tfm; 341 342 hash->length = crypto_shash_digestsize(tfm); 343 344 rc = crypto_shash_init(shash); 345 if (rc != 0) 346 return rc; 347 348 i_size = i_size_read(file_inode(file)); 349 350 if (i_size == 0) 351 goto out; 352 353 rbuf = kzalloc(PAGE_SIZE, GFP_KERNEL); 354 if (!rbuf) 355 return -ENOMEM; 356 357 while (offset < i_size) { 358 int rbuf_len; 359 360 rbuf_len = integrity_kernel_read(file, offset, rbuf, PAGE_SIZE); 361 if (rbuf_len < 0) { 362 rc = rbuf_len; 363 break; 364 } 365 if (rbuf_len == 0) { /* unexpected EOF */ 366 rc = -EINVAL; 367 break; 368 } 369 offset += rbuf_len; 370 371 rc = crypto_shash_update(shash, rbuf, rbuf_len); 372 if (rc) 373 break; 374 } 375 kfree(rbuf); 376 out: 377 if (!rc) 378 rc = crypto_shash_final(shash, hash->digest); 379 return rc; 380 } 381 382 static int ima_calc_file_shash(struct file *file, struct ima_digest_data *hash) 383 { 384 struct crypto_shash *tfm; 385 int rc; 386 387 tfm = ima_alloc_tfm(hash->algo); 388 if (IS_ERR(tfm)) 389 return PTR_ERR(tfm); 390 391 rc = ima_calc_file_hash_tfm(file, hash, tfm); 392 393 ima_free_tfm(tfm); 394 395 return rc; 396 } 397 398 /* 399 * ima_calc_file_hash - calculate file hash 400 * 401 * Asynchronous hash (ahash) allows using HW acceleration for calculating 402 * a hash. ahash performance varies for different data sizes on different 403 * crypto accelerators. shash performance might be better for smaller files. 404 * The 'ima.ahash_minsize' module parameter allows specifying the best 405 * minimum file size for using ahash on the system. 406 * 407 * If the ima.ahash_minsize parameter is not specified, this function uses 408 * shash for the hash calculation. If ahash fails, it falls back to using 409 * shash. 410 */ 411 int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash) 412 { 413 loff_t i_size; 414 int rc; 415 struct file *f = file; 416 bool new_file_instance = false, modified_flags = false; 417 418 /* 419 * For consistency, fail file's opened with the O_DIRECT flag on 420 * filesystems mounted with/without DAX option. 421 */ 422 if (file->f_flags & O_DIRECT) { 423 hash->length = hash_digest_size[ima_hash_algo]; 424 hash->algo = ima_hash_algo; 425 return -EINVAL; 426 } 427 428 /* Open a new file instance in O_RDONLY if we cannot read */ 429 if (!(file->f_mode & FMODE_READ)) { 430 int flags = file->f_flags & ~(O_WRONLY | O_APPEND | 431 O_TRUNC | O_CREAT | O_NOCTTY | O_EXCL); 432 flags |= O_RDONLY; 433 f = dentry_open(&file->f_path, flags, file->f_cred); 434 if (IS_ERR(f)) { 435 /* 436 * Cannot open the file again, lets modify f_flags 437 * of original and continue 438 */ 439 pr_info_ratelimited("Unable to reopen file for reading.\n"); 440 f = file; 441 f->f_flags |= FMODE_READ; 442 modified_flags = true; 443 } else { 444 new_file_instance = true; 445 } 446 } 447 448 i_size = i_size_read(file_inode(f)); 449 450 if (ima_ahash_minsize && i_size >= ima_ahash_minsize) { 451 rc = ima_calc_file_ahash(f, hash); 452 if (!rc) 453 goto out; 454 } 455 456 rc = ima_calc_file_shash(f, hash); 457 out: 458 if (new_file_instance) 459 fput(f); 460 else if (modified_flags) 461 f->f_flags &= ~FMODE_READ; 462 return rc; 463 } 464 465 /* 466 * Calculate the hash of template data 467 */ 468 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data, 469 struct ima_template_desc *td, 470 int num_fields, 471 struct ima_digest_data *hash, 472 struct crypto_shash *tfm) 473 { 474 SHASH_DESC_ON_STACK(shash, tfm); 475 int rc, i; 476 477 shash->tfm = tfm; 478 479 hash->length = crypto_shash_digestsize(tfm); 480 481 rc = crypto_shash_init(shash); 482 if (rc != 0) 483 return rc; 484 485 for (i = 0; i < num_fields; i++) { 486 u8 buffer[IMA_EVENT_NAME_LEN_MAX + 1] = { 0 }; 487 u8 *data_to_hash = field_data[i].data; 488 u32 datalen = field_data[i].len; 489 u32 datalen_to_hash = 490 !ima_canonical_fmt ? datalen : cpu_to_le32(datalen); 491 492 if (strcmp(td->name, IMA_TEMPLATE_IMA_NAME) != 0) { 493 rc = crypto_shash_update(shash, 494 (const u8 *) &datalen_to_hash, 495 sizeof(datalen_to_hash)); 496 if (rc) 497 break; 498 } else if (strcmp(td->fields[i]->field_id, "n") == 0) { 499 memcpy(buffer, data_to_hash, datalen); 500 data_to_hash = buffer; 501 datalen = IMA_EVENT_NAME_LEN_MAX + 1; 502 } 503 rc = crypto_shash_update(shash, data_to_hash, datalen); 504 if (rc) 505 break; 506 } 507 508 if (!rc) 509 rc = crypto_shash_final(shash, hash->digest); 510 511 return rc; 512 } 513 514 int ima_calc_field_array_hash(struct ima_field_data *field_data, 515 struct ima_template_desc *desc, int num_fields, 516 struct ima_digest_data *hash) 517 { 518 struct crypto_shash *tfm; 519 int rc; 520 521 tfm = ima_alloc_tfm(hash->algo); 522 if (IS_ERR(tfm)) 523 return PTR_ERR(tfm); 524 525 rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields, 526 hash, tfm); 527 528 ima_free_tfm(tfm); 529 530 return rc; 531 } 532 533 static int calc_buffer_ahash_atfm(const void *buf, loff_t len, 534 struct ima_digest_data *hash, 535 struct crypto_ahash *tfm) 536 { 537 struct ahash_request *req; 538 struct scatterlist sg; 539 struct crypto_wait wait; 540 int rc, ahash_rc = 0; 541 542 hash->length = crypto_ahash_digestsize(tfm); 543 544 req = ahash_request_alloc(tfm, GFP_KERNEL); 545 if (!req) 546 return -ENOMEM; 547 548 crypto_init_wait(&wait); 549 ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG | 550 CRYPTO_TFM_REQ_MAY_SLEEP, 551 crypto_req_done, &wait); 552 553 rc = ahash_wait(crypto_ahash_init(req), &wait); 554 if (rc) 555 goto out; 556 557 sg_init_one(&sg, buf, len); 558 ahash_request_set_crypt(req, &sg, NULL, len); 559 560 ahash_rc = crypto_ahash_update(req); 561 562 /* wait for the update request to complete */ 563 rc = ahash_wait(ahash_rc, &wait); 564 if (!rc) { 565 ahash_request_set_crypt(req, NULL, hash->digest, 0); 566 rc = ahash_wait(crypto_ahash_final(req), &wait); 567 } 568 out: 569 ahash_request_free(req); 570 return rc; 571 } 572 573 static int calc_buffer_ahash(const void *buf, loff_t len, 574 struct ima_digest_data *hash) 575 { 576 struct crypto_ahash *tfm; 577 int rc; 578 579 tfm = ima_alloc_atfm(hash->algo); 580 if (IS_ERR(tfm)) 581 return PTR_ERR(tfm); 582 583 rc = calc_buffer_ahash_atfm(buf, len, hash, tfm); 584 585 ima_free_atfm(tfm); 586 587 return rc; 588 } 589 590 static int calc_buffer_shash_tfm(const void *buf, loff_t size, 591 struct ima_digest_data *hash, 592 struct crypto_shash *tfm) 593 { 594 SHASH_DESC_ON_STACK(shash, tfm); 595 unsigned int len; 596 int rc; 597 598 shash->tfm = tfm; 599 600 hash->length = crypto_shash_digestsize(tfm); 601 602 rc = crypto_shash_init(shash); 603 if (rc != 0) 604 return rc; 605 606 while (size) { 607 len = size < PAGE_SIZE ? size : PAGE_SIZE; 608 rc = crypto_shash_update(shash, buf, len); 609 if (rc) 610 break; 611 buf += len; 612 size -= len; 613 } 614 615 if (!rc) 616 rc = crypto_shash_final(shash, hash->digest); 617 return rc; 618 } 619 620 static int calc_buffer_shash(const void *buf, loff_t len, 621 struct ima_digest_data *hash) 622 { 623 struct crypto_shash *tfm; 624 int rc; 625 626 tfm = ima_alloc_tfm(hash->algo); 627 if (IS_ERR(tfm)) 628 return PTR_ERR(tfm); 629 630 rc = calc_buffer_shash_tfm(buf, len, hash, tfm); 631 632 ima_free_tfm(tfm); 633 return rc; 634 } 635 636 int ima_calc_buffer_hash(const void *buf, loff_t len, 637 struct ima_digest_data *hash) 638 { 639 int rc; 640 641 if (ima_ahash_minsize && len >= ima_ahash_minsize) { 642 rc = calc_buffer_ahash(buf, len, hash); 643 if (!rc) 644 return 0; 645 } 646 647 return calc_buffer_shash(buf, len, hash); 648 } 649 650 static void __init ima_pcrread(u32 idx, struct tpm_digest *d) 651 { 652 if (!ima_tpm_chip) 653 return; 654 655 if (tpm_pcr_read(ima_tpm_chip, idx, d) != 0) 656 pr_err("Error Communicating to TPM chip\n"); 657 } 658 659 /* 660 * Calculate the boot aggregate hash 661 */ 662 static int __init ima_calc_boot_aggregate_tfm(char *digest, 663 struct crypto_shash *tfm) 664 { 665 struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} }; 666 int rc; 667 u32 i; 668 SHASH_DESC_ON_STACK(shash, tfm); 669 670 shash->tfm = tfm; 671 672 rc = crypto_shash_init(shash); 673 if (rc != 0) 674 return rc; 675 676 /* cumulative sha1 over tpm registers 0-7 */ 677 for (i = TPM_PCR0; i < TPM_PCR8; i++) { 678 ima_pcrread(i, &d); 679 /* now accumulate with current aggregate */ 680 rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE); 681 } 682 if (!rc) 683 crypto_shash_final(shash, digest); 684 return rc; 685 } 686 687 int __init ima_calc_boot_aggregate(struct ima_digest_data *hash) 688 { 689 struct crypto_shash *tfm; 690 int rc; 691 692 tfm = ima_alloc_tfm(hash->algo); 693 if (IS_ERR(tfm)) 694 return PTR_ERR(tfm); 695 696 hash->length = crypto_shash_digestsize(tfm); 697 rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm); 698 699 ima_free_tfm(tfm); 700 701 return rc; 702 } 703